Field of the Invention
The present invention relates to an exposure apparatus, a method thereof, and a method of manufacturing an article.
Description of the Related Art
As an apparatus used in a manufacturing process (lithography process) of a semiconductor device or the like, there is an exposure apparatus that transfers a mask pattern to a substrate. In such an exposure apparatus, the surface of the substrate needs to be arranged accurately on an imaging plane (focus plane) of a projection optical system so a mask pattern will overlap a shot region on the substrate with high accuracy.
Japanese Patent Laid-Open No. 2015-130407 proposes, for a scan exposure apparatus that performs an exposure process by scanning a substrate, a method of correcting the misalignment of the substrate surface that has been caused by a manufacturing error of a control system, a measurement error of a measurement device, a control error of the control system, or the like. Japanese Patent Laid-Open No. 2004-111995 proposes, for an exposure apparatus employing a step-and-repeat method, a method of correcting the misalignment of the substrate surface in a direction (Z direction) parallel to an optical axis of a projection optical system which is caused by driving a substrate stage in a direction perpendicular (X-Y direction) to the optical axis. Japanese Patent Laid-Open No. 2000-208391 proposes, for an exposure apparatus employing the step-and-repeat method, a method of performing focus measurement accurately before the exposure region is reached.
Generally, in an exposure apparatus, a focusing operation of arranging a substrate surface on a focus plane is performed by feedback control to increase the accuracy. On the other hand, increasing the speed of the focusing operation is an important requirement for improving throughput. To improve the throughput, it is possible to consider using methods such as increasing the acceleration of the movement of a substrate stage, performing focus measurement in advance by relaxing the settling tolerance of the substrate stage, or the like. However, in such a case, measurement errors can increase since the focus measurement will be performed in a state in which a deviation of the substrate stage is left with respect to a target position. Hence, a more effective correction is required.